1. Technical Field
The present invention relates to an electro-optical device, in which a plurality of thin films are laminated on a substrate and transistors are formed by a part of the plurality of laminated thin films, and an electronic apparatus.
2. Related Art
As is well known, an electro-optical device, for example, a light-transmissive liquid crystal device is configured such that liquid crystal is interposed between two substrates, such as a glass substrate, a quartz substrate, and a silicon substrate. In addition, for example, pixel electrodes and switching elements, such as thin film transistors, are arrayed in a matrix on one of the substrates and counter electrodes are arrayed on the other substrate. Image display is realized by changing an optical characteristic of a liquid crystal layer interposed between both the substrates in response to an image signal.
Furthermore, an element substrate on which transistors are arrayed and a counter substrate disposed opposite the element substrate are separately manufactured. The element substrate and the counter substrate are formed by laminating a semiconductor thin film, an insulating thin film, or a conductive thin film having a predetermined pattern on a quartz substrate, for example. That is, the element substrate and the counter substrate are formed by repeating processes of forming various kinds of films and a photolithographic process for respective layers.
In this case, a plurality of transistors provided for respective pixel electrodes are formed at intersections of data lines, which are used to supply image signals to pixel electrodes, and scanning lines, which are used to supply ON signals to transistors, in a display region of a liquid crystal device.
In addition, a transistor is configured to include: a semiconductor layer having an LDD structure including a channel region, a source region, and a drain region; a gate insulating layer laminated on the semiconductor layer so as to cover the semiconductor layer in plan view; and a gate electrode laminated on the gate insulating layer so as to be opposite to the channel region.
In this case, when light is incident on the channel region of the semiconductor layer of the transistor, the transistor malfunctions and display unevenness, crosstalk, and flickering resulting from an off-leakage current occur in the liquid crystal device. In addition, a display contrast decreases.
In view of the above problems, a configuration of a liquid crystal device capable of preventing light from being incident on a channel region of a semiconductor layer by providing a light shielding layer, which covers a lower side of the semiconductor layer in plan view, below the semiconductor layer and providing a light shielding layer, which covers an upper side of the semiconductor layer in plan view, above the semiconductor layer is known. For example, JP-A-2003-337553 discloses such configuration.
The liquid crystal device disclosed in JP-A-2003-337553 has a configuration in which scanning lines serve as a light shielding layer that covers a lower side of a semiconductor layer in plan view and electrodes of storage capacitors that hold voltages of pixel electrodes and data lines serve as a light shielding layer that covers an upper side of the semiconductor layer in plan view.
Furthermore, the liquid crystal device disclosed in JP-A-2003-337553 has a configuration in which extended portions for defining opening regions of pixels are provided for the electrodes of the storage capacitors, which serve as a light shielding layer that covers the upper side of the semiconductor layer, at intersections between the data lines and the scanning lines where the semiconductor layer is formed. In other words, a technique of reliably blocking light, which is incident on the channel region of the semiconductor layer in the perpendicular or oblique direction from an upper side, without decreasing an aperture ratio of each pixel by adopting the configuration in which a wide light shielding layer is formed at the intersections is disclosed in JP-A-2003-337553.
However, in the configuration of the liquid crystal device disclosed in JP-A-2003-337553, a light-transmissive insulating layer having a predetermined thickness is laminated between a semiconductor layer and an upper light shielding layer and between the semiconductor layer and a lower light shielding layer. That is, since the semiconductor layer is laminated so as to be apart from the upper and lower light shielding layers by a predetermined distance, it was not sufficient to reliably block light from being incident on the channel region of the semiconductor layer only with the upper and lower light shielding layers.
In addition, a gate electrode is formed only on the channel region of the semiconductor layer. Accordingly, a step difference occurs in a region where the gate electrode is formed and other portions of the semiconductor layer.
In addition, a data line is electrically connected to a source region of the semiconductor layer. For this reason, when a high dielectric constant layer that forms a light shielding layer is formed on the source region, coupling between a data line and the light shielding layer occurs. As a result, an electrical characteristic deteriorates.